/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.example.android.apis.graphics;

import android.content.Context;
import android.graphics.*;
import android.os.Bundle;
import android.view.*;

import java.nio.IntBuffer;
import java.nio.ShortBuffer;

public class BitmapPixels extends GraphicsActivity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(new SampleView(this));
	}

	private static class SampleView extends View {
		private Bitmap mBitmap1;
		private Bitmap mBitmap2;
		private Bitmap mBitmap3;

		// access the red component from a premultiplied color
		private static int getR32(int c) {
			return (c >> 0) & 0xFF;
		}

		// access the red component from a premultiplied color
		private static int getG32(int c) {
			return (c >> 8) & 0xFF;
		}

		// access the red component from a premultiplied color
		private static int getB32(int c) {
			return (c >> 16) & 0xFF;
		}

		// access the red component from a premultiplied color
		private static int getA32(int c) {
			return (c >> 24) & 0xFF;
		}

		/**
		 * This takes components that are already in premultiplied form, and
		 * packs them into an int in the correct device order.
		 */
		private static int pack8888(int r, int g, int b, int a) {
			return (r << 0) | (g << 8) | (b << 16) | (a << 24);
		}

		private static short pack565(int r, int g, int b) {
			return (short) ((r << 11) | (g << 5) | (b << 0));
		}

		private static short pack4444(int r, int g, int b, int a) {
			return (short) ((a << 0) | (b << 4) | (g << 8) | (r << 12));
		}

		private static int mul255(int c, int a) {
			int prod = c * a + 128;
			return (prod + (prod >> 8)) >> 8;
		}

		/**
		 * Turn a color int into a premultiplied device color
		 */
		private static int premultiplyColor(int c) {
			int r = Color.red(c);
			int g = Color.green(c);
			int b = Color.blue(c);
			int a = Color.alpha(c);
			// now apply the alpha to r, g, b
			r = mul255(r, a);
			g = mul255(g, a);
			b = mul255(b, a);
			// now pack it in the correct order
			return pack8888(r, g, b, a);
		}

		private static void makeRamp(int from, int to, int n, int[] ramp8888,
				short[] ramp565, short[] ramp4444) {
			int r = getR32(from) << 23;
			int g = getG32(from) << 23;
			int b = getB32(from) << 23;
			int a = getA32(from) << 23;
			// now compute our step amounts per componenet (biased by 23 bits)
			int dr = ((getR32(to) << 23) - r) / (n - 1);
			int dg = ((getG32(to) << 23) - g) / (n - 1);
			int db = ((getB32(to) << 23) - b) / (n - 1);
			int da = ((getA32(to) << 23) - a) / (n - 1);

			for (int i = 0; i < n; i++) {
				ramp8888[i] = pack8888(r >> 23, g >> 23, b >> 23, a >> 23);
				ramp565[i] = pack565(r >> (23 + 3), g >> (23 + 2),
						b >> (23 + 3));
				ramp4444[i] = pack4444(r >> (23 + 4), g >> (23 + 4),
						b >> (23 + 4), a >> (23 + 4));
				r += dr;
				g += dg;
				b += db;
				a += da;
			}
		}

		private static IntBuffer makeBuffer(int[] src, int n) {
			IntBuffer dst = IntBuffer.allocate(n * n);
			for (int i = 0; i < n; i++) {
				dst.put(src);
			}
			dst.rewind();
			return dst;
		}

		private static ShortBuffer makeBuffer(short[] src, int n) {
			ShortBuffer dst = ShortBuffer.allocate(n * n);
			for (int i = 0; i < n; i++) {
				dst.put(src);
			}
			dst.rewind();
			return dst;
		}

		public SampleView(Context context) {
			super(context);
			setFocusable(true);

			final int N = 100;
			int[] data8888 = new int[N];
			short[] data565 = new short[N];
			short[] data4444 = new short[N];

			makeRamp(premultiplyColor(Color.RED),
					premultiplyColor(Color.GREEN), N, data8888, data565,
					data4444);

			mBitmap1 = Bitmap.createBitmap(N, N, Bitmap.Config.ARGB_8888);
			mBitmap2 = Bitmap.createBitmap(N, N, Bitmap.Config.RGB_565);
			mBitmap3 = Bitmap.createBitmap(N, N, Bitmap.Config.ARGB_4444);

			mBitmap1.copyPixelsFromBuffer(makeBuffer(data8888, N));
			mBitmap2.copyPixelsFromBuffer(makeBuffer(data565, N));
			mBitmap3.copyPixelsFromBuffer(makeBuffer(data4444, N));
		}

		@Override
		protected void onDraw(Canvas canvas) {
			canvas.drawColor(0xFFCCCCCC);

			int y = 10;
			canvas.drawBitmap(mBitmap1, 10, y, null);
			y += mBitmap1.getHeight() + 10;
			canvas.drawBitmap(mBitmap2, 10, y, null);
			y += mBitmap2.getHeight() + 10;
			canvas.drawBitmap(mBitmap3, 10, y, null);
		}
	}
}
